Hello Toufiq,
ok got it. Setting an image, at the same time specifying a video and leaving video section "activated" puts in a the poster image and also resolves the issue of the additional request to the root document (this has been due to not specifying an image).
<video class="section-bg-video" autoplay muted playsinline loop poster="/images/06_Others/2023_12_31_og_graph_image_home.jpg"><source src="/https://dresden-hepcats.de/images/06_Others/2023_06_08_Solo_Jazz_Kurs_Big_Apple_Teaser_50MB.mp4" type="video/mp4"></video>
Whatsoever, this maybe an improvement for future development as this is not really straightforward from a user perspective? I think the relation between backgrund image und video, does not become clear ux-wise, at least for me. Also, when implementing a video with a normal add-on the is a dedicated section where you specify a poster.
Anyway, many thanks for resolving this :-).
Best regards,
Sascha